Dain A
Cytogenet Cell Genet. 1977;18(3):126-35. doi: 10.1159/000130757.
The X chromosomes of the male pronghorn (Antilocapra americana) is larger than the "original" type and carries a large segment of late-labelling chromatin. The Y chromosome has a late-labelling segment that appears to duplicate synchronously with that of the X. Both chromosomes have segments that label throughout the period of observation; that the X is about 4.7% of the haploid complement and approaches "original" proportions. The X chromosomes of the Rocky Mountain goat (Oreamnos americanus) appear to be of the "original" type, without marked late-labelling regions, and the Y chromosomes is small. The structure and origin of extra-large sex chromosomes are discussed.
雄性叉角羚（美洲叉角羚）的X染色体比“原始”类型更大，并且携带一大段晚标记染色质。Y染色体有一个晚标记区段，似乎与X染色体的该区段同步复制。在整个观察期内，两条染色体都有标记区段；X染色体约占单倍体组的4.7%，接近“原始”比例。落基山羊（美洲羊）的X染色体似乎是“原始”类型，没有明显的晚标记区域，Y染色体很小。文中讨论了超大性染色体的结构和起源。
